Safety pilot for gas burners and the like



July 2, 1935.

oVJ. LEINS SAFETY PILOT FOR GAS BURNERS AND THE LIKE Filed June 5, 1933 5 Sheets-Sheet 1 m ,f C J QNQ Q ZAVQ:WZ@@QQGQ@Q@: :11: 7 NM h e ooooooooooooo009.000 000 00 Jhwmfar: 3 0564/ Z s'ma July 2, 1-935. Q J LElNs 2,006,958

SAFETY PILOT FOR GAS BURNERS AND THE LIKE Filed June 5, 1955 s Sheets-Sheet s fizwwzifvrz 05060" J lavas & WW

Patented July 2, 1935 SAFETY PILOT FOR THE GAS commas AND K LIKE Oscar 'J. Leins, Milwaukee, Wis assignor to Milwaukee GasSpecialty Company, Milwaukee,

Wis a corporation of Wisconsin Application- June 5, 1933, Serial No. 674,294 '10 Claims. ((1158-1111) This invention relates to a safety pilot for gas burners and the like.

While the preferred embodiments which I shall describe hereinafter'in connection with the ti drawings are adapted for use with burners for water heaters and with heating devices for rooms, chambers, ovens and the like, it is to be understood that the invention is not to be limited to these particular uses, nor is it to be limited to the details of the particular embodiments illustrated and described. 1

Heating devices of the general type to which i the preferred embodiments of this invention relate comprise a main burner or heater and means for supplying the heating medium, that is, the gas, oil or electric current thereto. Controlling means is provided in the heating medium supply line for controlling the supply of heating medium to the main burner or heater and to prevent the escape of gas from the burner without being lighted at the burner such as otherwise might result if the flame at the burner is extinguished without shutting off the supply of heating medium, or if the valve or control means in the heating medium supply line is turned-on without lighting the gas 'which thereupon issues from the burner, safety pilots have been provided.

These safety pilots have usually consistedof a pilot tube connected to the heating medium supply line anterior tothe control means and adapted to deliver a relatively restricted supply of gas or the like at a safety pilot outlet adjae cent the main burner or heater. A thermally operated device adjacent and directly subject to the heat of the flame maintained at the safety pilot outlet has usually been provided for the purpose of shutting off the supply of heating medium to the burner or heater in the event that the pilot flame is extinguished accidentally or otherwise.

According to the present invention, instead of positioning the thermally operated device adjacent to the pilot outlet so that it will be influenced directly by the heat of the flame at the safety pilot outlet, I dispose a looped, coiled, or other suitable portion of the fuel or heating mediumsupply line for the safety pilot adjacent the safety pilot outlet to pre-heat by means of the safety pilot flame the fuel or heating medium supply for the safety pilot anterior to the safety pilot outlet. The thermally operated device is disposed in the path of the pro-heated supply of fuel for the safety pilot posterior to the preheating position and anterior to the safety pilot outlet to be under the direct thermal influence of the preheated fuel or heating medium supply for the safety pilot, and this thermally operated device is arranged to stop or shut off the fuel or heating medium supply to the main burner or heater when the safety pilot is extinguished.

One of the chief advantages of the present invention lies in its simplicity and safety and in freedom from trouble inherent in thermosensitivedevices exposed directly to the heat of the flame at the safety pilot outlet and in heating areas where vapors and other objectionable elements or actions'exist or occur: also in freedom of the thermostatic metal of the thermally operated device from the direct influence of constructional variations in the heating device.

Another advantage lies in the fact that the thermostatic element of the thermally operated device may be entirely enclosed and the thermally operated device may be mounted in position away. or remote from the safety pilot outlet as, for example, at and housed within an enclosure which, in the illustrated embodiment of the invention, is mounted upon one of the side walls of the heating device, although this, of course, may vary. The safety pilot control is directly related to the temperature of the preheated heating medium for the safety pilot, and this preheated heating medium has a direct and rapid influence on the thermostatic metal of the thermally operated device.

Other advantages and adaptations of the invention will be apparent from the following detailed description when taken in connection with the accompanying drawings, in which:

Figure 1 is a fragmentary top plan view of one embodiment of the present invention with the illustrated portion of the wall of the heating device in section;

Figure 2 is a fragmentary side elevational view of the embodiment shown in Figure 1;

Figure 3 is a fragmentary top plan view of an. electric safety vpilot control embodying the present invention;

Figure 4 is .a fragmentary side elevational view of the embodiment shown in Figure 3 and showing, more or less diagrammatically, the circuit connections therefor;

Figure 5 is a fragmentary detail section through the housing for the thermostatic element of the thermally operated device of Figures 1 and 2 and taken on the line 5-5 of Figure 1;

Figure 6 is a more or less diagrammatic vertical detail section through the diaphragm valve" of Figures 1 and 2 partially, in elevation and taken ;on the line 55 of Figure 1;

Figure 7 is a fragmentary detail section through the housing for the thermostatic element of the thermally operated device of Figures 3 and 4 and taken on the line of Figure 3; and

Figure 8 is a more oraless' diagrammatic vertical detail section through the solenoid valve of Figures 3 and 4 and taken on the line 8-8 of Figure 3.

Referring to the drawings, the heating device, only the side wall 5 of which is shown, has a main burner or heater 5.

The gas supply manifold is indicated at I. Gaseous fuel is led from the manifold 1 to the main burner 5 by way of a mixing head 8 through which air is admittedto the outer end of the feed pipe 9 in the usual manner well known in the art. The feed pipe 9 extends through the side wall 5 and its inner end is turned up and connected to the main burner 5 at III. The nozzle pipe I l, which leads from the manifold I into the mixing head 8 at the outer end of the feed pipe 9, is provided with the usual or any suitable or preferred gas cock l2 positioned between. the manifold 'and the mixing head end of the nozzle pipe II and adapted for controlling manually the supply of gaseous fuel from the manifold 'l to the main burner 5.

Gaseous fuel for the safety pilot, designated in its entirety at I5, is led from the manifold or heating medium supply pipe 1 through a fuel supply pipe or tube I5 connected to the manifold or pipe I posterior to the diaphragm valve. The pipe or tube l5 extends inwardly through .the side wall 5 and within the wall 5' the inner end of the tube I5 is looped back at l8 and connected to the housing l9 which encloses the bi-metallic element 28 (Figure 5) of the thermally operated device. The loop I8 is preferably made of metal, such as copper or aluminum, of relatively high speciflc heat properties, and the bight at the inner end of the loop is disposed directly above and adjacent the safety pilotoutlet 28' at the inner end of the safety pilot outlet tube 2| where it is subject to the heat of the safety pilot flame indicated at 22. The outer end of the tube 2| is'connected through a relatively restricted safety pilot outlet port 23 with the chamber 24 within the housing IS, the outer end of the lower looped part of the loop l8 having relatively unrestricted communication with thechamber 24, as shown- The housing I! is relatively compact for disposition in an opening 25 in the side wall 5, and it has an integral flange .25 which cooperates with the outer side of the wall 5 to close the opening 25, and which flange may be bolted or otherwise suitably secured to the wall 5. The housing l9 has formed therein, as by coring or in any suitable or preferred manner, an auxiliary chamber 35 separated from the chamber 24 by a partition 32,-which partition 32 has a port 33 for placing the chamber 24 in communication with the auxiliary chamber as will hereinafter appear. A bushing 34 threaded into the outer side of the housing l9 adjacent the chamber 38 has an axial passage 34' opening at its inner end into the chamber 35 and at its outer end to atmosphere for venting the chamber 35 to atmosphere as will hereinafter appear.

The diaphragm valve designated in its entirety at 35 is positioned in the manifold or heating medium supply pipe 1 anterior to the connection of the tube l5 and nozzle pipe with the heating medium supply line. This diaphragm valve 35 may be of any suitable or preferred form. The detailed construction of the illustrated valve is shown more or less diagrammatically and only to such extent as to impart a clear understanding of the illustrated embodiment of the present invention. The valve body 35 has the inlet 38 connected to the inlet side of the pipe 1 and an outlet 35 connected to the outlet side of the pipe. The

inlet 38 opens into the inlet chamber 45 and the outlet 39 leads from the outlet chamber 4|, these chambers 40 and 4| being separated by a partition 42 having a port 43 for connecting the chambers 48 and 4|. The port 43 has a surrounding seat upon which valve 44, having a correspondingly formed periphery, is adapted to seat toclose oif the gas supply to the main burner 5 and to the safety pilot.

The valve 44 is carried upon the lower end of a vertical stem 45 slidable in a bushing 45 threaded into the upper end of the valve body 35. The diaphragm housing 48 comprises two complementary diaphragm housing parts between the flanges 49, of which. the outer periphery of the diaphragm 58 is clamped as by means of suitable bolts or the like, not shown.' The diaphragm 58 is connected centrally at 52 to the valve stem 45 and is gas tight, thereby dividing the interior of the housing 48 into an upper chamber 53 and a lower chamber 54 separated therefrom.- A conduit or tube 55 leads from the upper chamber 53 and is connected at its opposite end at 55 to the auxiliary chamber 35 in the housing l8 for the thermally operated device.

, For the purpose of manually opening the valve 44, the stem 45 is shown as having a reduced upper end 58 extending upwardly through the boss on the upper part of the housing 48 and provided at its upper end with a finger piece or button 58 for manipulating the stem. To hold the valve 44 closed after it is moved down to closed position by the pressure imposed upon the top of the diaphragm 58 by the gas admitted to the upper diaphragm chamber 53 through the conduit 55, as will hereinafter appear, the button 55, or the upper end of the stem 45 is shown as provided with a pawl 52 pivoted at 53 and adapted to ride downwardly over annular teeth 54in the upper end of the boss 55, and to cooperate with these teeth 54 to latch the valve 44 in closed position. This valve latching means is merely illustrative and may vary widely, or it may be omitted, in which case the diaphragm 58 may be held down and the valve 44 held closed by maintenance of pressure in the chamber 53, or the diaphragm 58 may be self-holding in valve closed position after it is. flexed downwardly past center and into the position shown in dotted lines in Figure 6. The diaphragm 58 may be provided with annular corrugations 55 adjacent its outer periphery. Where the latching means shown is provided the valve is raised manually from closed position by grasping the button and pressing down slightly upon the upper shell part thereof against the tension of the leaf spring 58. This releases the pawl 52 from the teeth 54 and the valve is opened'by drawing the stem 45 upwardly to the position shown in full lines in Figure 6.

The diaphragm 58 is self-holding in this posiof the element-20 carries on a post or pin 12,

rigidly secured thereto, a valve member 13 which operates in the auxiliary chamber 33 into and out of cooperation with a seat at the outer end of the passage 33, and into and out of cooperation with a seat at the inner end of the vent passage 34'.

The operation of the embodiment of Figures 1, 2, 5 and 6 is as follows:

Assuming that the valve 44 is open, the gaseous fuel for the main burner 3 passes'from the pipe I through the nozzle pipe I,l, mixing head 8 where the desired air is admitted, and the gaseous mixture flows through the feed pipe 9 to the burner 6 from which it issues and burns at the top of the burner,- as well understood. The burner 6 thus supplied with gaseous fuel when ignited heats the desired space, water, or the like, or supplies heat which may be delivered from the heating'device 5 for use elsewhere.

At the same time, gaseous fuel for the safety pilot passes from the pipe I through the conduit l6, pro-heating loop or portion I8, chamber 24, passage 23 and tube 2|, from the outlet end 20' of which the safety pilot supply of gas issues and, when ignited, burns adjacent the main burner 6. extinguished with the pilot lighted, the pilot flame 22 will reignite the main burner. The valve 13 at this time is in the position shown in Figure-5 seated against and closing the outer end of the passage 33. Thepassage 34 is open and vents the auxiliary chamber 30 and, through it, the upper diaphragm chamber 53 and the conduit to atmosphere.

The gas supply for the safety pilot outlet 20' upon passing through the loop or pre-heating portion l8 of the tube I6 is pre-heated by the pilot flame 22, and upon passing through'the chamber 24 this pre-heated gas will impart direct thermal influence upon the bi-metallic element 20 to maintain the same in the position shown in Figure 5 and the valve 13 closed against theouter end of the passage 33. If the pilot flame 22 is extinguished,- the safety pilot supply of gas passing through the loop l8 will not be pre-heated by the pilot flame, and the absence of the direct thermal influence of this pre-heated' supply of fuel upon the bi-metallic element 20 will permit this element 20 to warp from the position shown in full lines in Figure 5 to the position shown in dotted lines opening the valve 13 away from the outer end of the passage 33 and closing it against the inner end of the vent passage 34'. This closes off the vent to atmosphere from the chamber 24 and places the chamber 24 in communication with the upper diaphragm chamber 53 through the passage 33, auxiliary chamber 30 and conduit 55. Thereupon, the pressure of the gas upon the top of the diaphragm 50 moves the same downwardly to the dotted line position (Figure 6) and the valve 44 into closed position upon the seat surrounding the port 43. This closing of the valve 44 closes If the main burner is accidentally or shuts off the supply of gas to the main burner 3 and also the supply of gas to the safety pilot outlet.- It is understood that the relative restrictlon of the passage 23 prevents the escape of gas from the chamber 24 and from the pilot outlet 20' in quantities sumcient to interfere with the closing of the valve 44 by the gas pressure upon the diaphragm 50 when the pilot flame is extin- 'guished.

From the foregoing, it will appear that, in

the event the safety pilot flame is quenched or extinguished, the absence of the pre-heating of thesafety pilot supply of fuel will permit the thermo-sensitive element to cause the diaphragm valve to close and prevent further flow of gas to the burnerand the safety pilot. In order to relight the pilot, the button 30 is grasped and manipulated to release the pawl 62, andthe valve 40 is then raised to open position and held open to liberate gas into the safety pilot tube. Hi, from where it passes through the loopl8, chamber 24 and tube 2|, to the pilot outlet where it is lighted. The valve is held open manually until sufficient pre-heated gases have passed through the thermo-sensitive chamber 24 to. warp the element 20 to its full line position,v in which position the valve I3 seats upon the outer end of the passage 33 and opens the vent 34' to atmosphere so that the diaphragmlill will remain raised under its own action and the valve will remain in open position. The diaphragm 50, which may be of spring metal or the like, is so distorted or under tension that when its central portion is raised in the manner described it will remain raised so long as the pressure of the gas supply to the safety pilot is not imposed thereon. In order to light the burner, the gas cock I2 is opened to set up the desired supply of gas to the burner which is ignited by the pilot flame 22.

In the embodiment of Figures 3, 4, 7 and 8, the side wall of the heating device is shown fragmentarily at 5, the main burner or heater at 6', and the gas 201' heating medium supply manifold or line is indicated at I. As-before, gaseous fuel is led from the manifold 1' to the main burner 6' by way of the mixing head 8, through which air is admitted to the outer end of the feed pipe 9, which pipe 9 extends through an opening in the side wall 5' and has its inner end turned up and connected to the main burner 6 at H). The nozzle pipe H which leads from the manifold 1' into the mixing head 8 is profrom the manifold I to the main burner 6'.

The gaseous fuel for the safety pilot, designated in its entirety at I5, is led from the. manifold or heating medium supply pipe 1' through a fuel supply tube or conduit l6 connected to the manifold or pipe I posterior to the solenoid valve 15. The pipe or tube It extends inwardly through the side wall 5, and within the wall 5' the inner end of the tube I6 is looped back at [3 and connected to the housing l9 which encloses the bi-metallic element 20" (Figure 7) of the thermally operated device. As before, the loop [8' is preferably made of metal, such as copper or aluminum, of relatively high specific heat properties, and the bight at the innerend of the loop is disposed directly above and adjacent-the safety pilot outlet 20" at the inner end of the safety pilot outlet tube 2| where it is subject to the heat of the safety pilot flame indicated at 22. The outer end of the fore, for disposition in an opening 25 in the-side wall 5', and it has an outer cover plate 18 suitably attached thereto. The cover plate 16 is preferably formed of suitable insulating material,

and mounted in this plate and insulated from each other are a pair of electric contacts 11 and 18. One contact 11 is connected by a conductor 18 (Figure 4) to one side of the secondary of a transformer 88, the other side of the secondary of which transformer is connected to one terminal 8| of the solenoid valve 15. The other terminal 82 of the solenoid valve is connected by a conductor 13 to the other contact 18 on the insulating plate 16.

The solenoid valve 15 is positioned in the manifold or heating medium supply pipe 1' anterior -to the connection of the tube l8, and nozzle pipe II with the heating medium supply line. This solenoid valve 15 may be of any suitable or preferred form. The detailed construction of the illustrated valve is shown more or less diagrammatically and, as is the case with burner 8' and to the safety pilot.

body 36' is shown as having the inlet chamberthe diaphragm valve of the preceding embodiment only to suchextent as to impart a clear understanding of the illustrated embodiment of the present invention. The annular solenoid winding 85 (Figure 8) is connected across the terminals 8| and 82 and has the central opening 86 in which the core 81 is movable axially. The core 81 has a depending stem 45 on the lower end of which is a valve 44' whichis adapted to .seat upon the cooperating seatsurrounding the port 83 to close ofl the gas supply to the-main The valve 48' andthe outlet chamber 8| separated by the partition 42', which partition is provided with the connecting port opening 88'.

The solenoid winding 85 and core 81 may be enclosed in a suitable housing 88 which may be mounted upon the top of the valve body 85' in the manner in which the diaphragm housing is mounted upon the top of the valvebody 28 of the preceding embodiment. The terminals 8| and 82 may be mounted in insulated relation on the top of the housing 88. The valve 88' may close by gravity upon deenergization of the winding 85 as will hereinafter appear, and, if desired, a coiled spring 82 may be interposed between the topof the core 81 and the top of the housing 88 to close or assist in closing the valve 84 upon its seat. For the purpose of manually opening the valve 84' the core 81 has astem 82 extending upwardly through the top of the housing 88 and provided at its upper end with a finger piece or button 83 for manipulating the valve passage 23 and tube 2|, to the safety pilot outlet 28". This element is composed of Joined strips 88 and I88 of different metals having diflerent coefficients of expansion with the strip having the greatest coefficient of expension positioned on the inner side of the element, as viewed in Figure '1. The upper end of the element 28" is anchored at I82 in electrical contact with the contact 11 and thelower end of the element 28" is adapted to contact with the contact 18 to complete the circuit through the.

solenoid winding 85 and is adapted to be warped away from the contact 18 to open this circuit and deenergize the winding 85.

The operation of the embodiment of Figur 3, 4, '1 and 8, is as follows:

With the valve 44' open as shown, the gaseous fuel for the maimburner 5' passes from the pipe 1 through the nozzle pipe ll, mixing head 8' where the desired'air is admitted, and the gaseous mixture flows through the feed pipe 8' to the burner 6' from which it issues and burns at the top of the burner. As before, the burner 6' thus supplied with gaseous fuel when ignited heats the desired space, water, or the like, or supplies heat which may be delivered from the heating device 5' for use elsewhere.

At the same time, gaseous fuel for the safety pilot passes from the pipe 1 through the conduit l8, .pre-heating loop or portion I8, chamtion I8, is pre-heated by thepilot flame 22',

and, upon passing through the chamber 24', this pre-heated gas will impart direct thermal influence upon the bi-metallic element 28", as before, to maintain. the same in the position shown in full lines in Figure 7, and the solenoid winding 85 energized to hold the valve 84' open.

If the pilot flame 22 is extinguished, the safety pilot supply of gas passing through the loop l8 will not be pre-heated by the pilot flame 22' and the absence of the direct thermal'influence of this pre-heated supply of fuel upon the bi-metallic element 28" will permit this element 28" to warp from the position shown in full lines in Figure '1 to the position shown in dotted lines, the lower-end of the element moving out of contact with the terminal 18 and opening the circuit for the solenoid winding 85 thereby deenergizing this winding. The core 81, stem 45' and valve 84 thereupon drop and/or are forced downwardly by the spring 82' moving the valve 44' to closed position to shut off the supply of gas to the main burner 8' and also the supply of gas to the safety pilot outlet In order to relight the pilot, the button 88 is grasped and the valve 44 lifted upwardly thereby to the desired open position This liberates gas into the safety pilot tube I5 from where it passes through the loop l8, chamber 24' and tube 2| to the pilot outlet where it is ignited. The valve 'is held open manually until sumcient pre-heated gases have passed through the thermo-sensitive chamber 24' to warp the element 28" to its full line position, in which position its lower and contacts the terminal 18 thereby closing the circuit through the winding 85 which thereupon operates to hold the valve 48 in open position. In the event of failure of the electric circuit, the valve 44' drops or is moved to closed position to cut of! the gas supply. In order to light the. burner 6', the gas cock I! is opened to set up the desired supply of gas to the burner which is ignited by the pilot flame 22'.

I do not intend to'be limited to the precise details nor to the particular uses shown or described.

I claim:

1. In combination, a main burner, a safety pilot for maintaining a pilot flame adjacent said main burner, means for delivering fuel to saidv main burner and to the safety pilot, means for pre-heating the fuel delivered to said safety pilot, and means for controlling the supply of fuel to the burner by the temperature of the fuel supply to said safety pilot.

2. In combination, a main burner, a safety pilot for maintaining a pilot flame adjacent said "main burner, means for delivering fuel to said lot, means for controlling the supply of fuel to the burner by the temperature of the fuel supply to said safety pilot, said last means com prising a bi-metallic element in the path of fuel supply to the'safety pilot, and a valve for the fuel supply for the main burner operatively connected to said bi-metallic element.

4. A safety pilot comprising a housing, a conduit connected to said housing for delivering.

fuel thereto, a tube leading from said housing and having a pilot outlet for maintaining a pilot flame, a bi-metallic element disposed within said housing and controlled by the temperature of the fuel delivered through said housing to said pilot outlet, a fuel supply line, a valve in said fuel supply line, and means controlled by said bi-metallic element and operative to close said valve when the pilot flame is extinguished.

5. In combination, a burner, a fuel supply line therefor, a safety pilot for maintaining a pilot flame adjacent said burner, said safety pilot comprising a housing, a tube leading from said housing and having apilot' outlet, a conduit connected between the fuel supply line and said housing for delivering fuel for the safety pilot to said housing, said conduit having a pre-heating portion anterior and adjacent the pilot outlet, a solenoid valve in the fuel supply line, an electric circuit for said valve, contacts connected into said circuit and disposed adjacent said housing, and a bi-metallic element disposed within said housing to be subject to'the temperature of the fuel supply for the safety pilot and cooperating with said contacts to control the circuit for said valve.

6. In combination, a burner, a fuel supply line therefor, a safety pilot for maintaining a pilot flame adjacent said burner, said safety pilot comprising a housing having a vent to atmosphere, a tube leading from said housing and having a pilot outlet, a. conduit connected between the fuel supply line and said housing for delivering fuel for the safety pilot to said housing, said conduit having a pre-heating portion anterior and adjacent the pilot outlet, a diaphragm valve in the fuel supply line, a connection between the housing and the, diaphragm valve, and a bi-metallio element disposed within said housing to be subject to (the temperature of the fuel supply for the safety pilot and operable to vent the connection to the diaphragm valve to atmosphere 'and to connect said connection to the conduit connected between the fuel supply line and said housing.

7. In combination, a burner, a gaseous fuel supply line for the burner, a safety pilot connected to said gaseous fuel supply line, said safety pilot being positioned to pre-heat the fuel delivered from said fuel supply line to said safety pilot, andmeans responsive to the temperature of the pre-heated fuel for said safety pilot and operative to control the delivery of fuel to said burner.

8. In combination, a gas burner, a safety pilot therefor, a fuel supply line for the burner and said safety pilot, a valve in said fuel supply line, means delivering fuel from said supply line posterior to said valve to said safety pilot to maintain a pilot flame for the burner, saidsafety pilot being positioned to pre-heat the fuel supply line for said heater, means for passing a portion of the gaseous fuel in a path out of the main path to the heater, means in the path of said portion of said gaseous fuel and remote from the main path of gaseous fuel for preheating the portion of gaseous fuel passed out of the main path of the heater without preheating the gaseous fuel in the main path to the heater, and temperature responsive means actuated by the temperature of the'pre-heated portion of the gaseous fuel for controlling the de- Every of fuel through said gaseous fuel supply 10. In combination, a pair of fuel supply tubes, 2. housing having a main chamber for connecting said tubes and an auxiliary chamber having an air vent to atmosphere, a connecting port between said chambers, a pressure-operated valve connected to the auxiliary chamber and adapted to be vented to atmosphere by the air vent for said auxiliary chamber, a valve member disposed within said auxiliary chamber and cooperable with the connecting port between the chambers to close the same in one position of the valvemember and with the air vent for the auxiliary chamber to close said air vent and open said port inthe other position of said valve member, the opening of the port between the main and auxiliary chambers permitting a building up of pressure at the pressure operated valve from one of said fuel supply tubes and the closing of said port shutting off the pressure operated valve against building up of pressure from said fuel supply tube, and a bi-metallic element disposed within said main chamber and controlling said valve and thereby the application of pressure to said pressure operated valve.

OSCAR J. LEINS.

CERTIFICATE OF CORRECTION. Patent No. 2. 006,958. I i I July 2, 1935.

OSCAR 1-. gLnms. I t ishereby certified that error;app'ears in the printed specification of the above numbered patent requiring correction asdollows: Page 5, second column, line 42, claim 9. for "of" second occurrence read to; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the .case' in the Patent Office.

Signed and "sealed this 13th day 'of August, A. D, 1935.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

